Halogen lamp

ABSTRACT

A lamp having a bulb in which a halide substance and a nitrogen or inert gas are sealed. The halide substance to be sealed is in the form of chloroform which amounts to 0.01 to 0.10 micromol per cubic centimeter of the volume of the bulb.

[54] HALUGEN LAMP [72] inventor:

Reierences Cited' Yooji Yuge, Yokohama, Japan [73] Assignee: Tokyo Shibaura Electric Co., Ltd., UNITED STATES PATENTS Jampens et al.....................313/223 X Kawasaki-shi, Japan Apr. 16, 1970 [22] Filed:

Primary Examiner-Raymond F. Hossfeld Attorney-George B. Oujevolk 211' Appl.No.:

T [30] Foreigt Application Priority Data I ABS llACT Apt 16 1969 A lamp having a bulb m which a hallde substance and a Japan..............................;...44/29248 nitrogen or inert gas are sealed. The halide substance to be sealed is in the form of chloroform which amounts to 0.01 to 313/174, 313/222, 3 2 0.10 micromol per cubic centimeter of the volume of the bulb.

.llmlk 1/50 313/174, 222, 223

1 Claim, 3 Drawing Figures [58] Field ofSearch PATENTEDFEB22 I972 SHEET 1 [1F 2 FBG.

III/ I ULI INVENTOR.

MM M This invention relates to lamps and more particularly to a halogen lamp in which an organic halide is sealed.

A halogen is known which effects a so-called regenerating halogen cycle in which a vaporized metal from the filament and a halogen sealed in the bulb are combined at a portion of the inner wall of the bulb maintained at relatively low temperatures during the operation of the lamp, and the halogenmetal compound is evaporated therefrom and dissociated at a portion of the filament maintained at relatively high temperatures depositing metal on it. The halogen is sealed either alone or in the form ofa compound. In the former case, a blackening phenomenon at the bulb wall and an etching of the filament are excessive so that halogen is now usually employed in the form of its compound. Halogen compounds heretofore in use, however, are still not satisfactory in that they do not serve to fully eliminate the above two adverse phenomena. For example, hydrogen chloride (HCl) in common use is known to have the following disadvantages. Hydrogen which is chloride strongly reactive to water reacts during manufacturing processes, with water remaining or present in and on manufacturing tool elements, such as piping for feeding HCl from a container into the bulb, and valves provided thereto, and

eventually corrodes the tool elements, so that the tool elements become less durable. The reaction with water also takes place within the bulb, thereby causing the filament and anchor supporting the filament to be corroded. In addition, in the case of HCl, the permissible range of the amount of incorporation is greatly limited. The amount of incorporation in excess will result in the occurrence of the etching while a lesser amount is subject to the blackening phenomena, with the result that the yield of the product is very small.

According to the halogen lamp of this invention, chloroform (CHCI is used as halide and is sealed in the amount of 0.01 to 0.10 micromol per cubic centimeter of the inner volume of the bulb, together with an inert gas and/or a nitrogen gas. Chloroform is less reactive to water so that corrosion of components used in the manufacture and of the filament and anchors mounted in the bulb can be avoided. Further, the permissible range of the amount of incorporation of the material can be relatively widely selected, so that the yield of production is excellent.

This invention can be more fully understood from the following detailed description when taken in connection with reference to the accompanying drawings, in which:

FIG. 1 is a front elevation of a halogen lamp embodying this invention;

FIG. 2 shows a perspective view ofa modification of the invention; and

FIG. 3 is a diagram showing the comparison of the properties of a lamp made according to the present invention in which only chloroform is sealed therein with the properties of a lamp made by added hydrogen or chlorine.

Referring to FIG. I, the halogen lamp having a rating of 24 v. 150 w. comprises a transparent cylindrical glass bulb or envelope I of 10 mm. in diameter and 60 mm. in length, having therein a transverse filament ofa tungsten coil 2, Both ends of the filament are connected via lead wires 3 and metal foils 4 embedded hermetically in squeezed portions of the bulb 1 to terminal pins 5 protruding outwardly from the base of the lamp. The bulb is sealed with 0.05 micromol of trichloromethane or chloroform (CHCl per cubic centimeter of the inner volume of the bulb and with an inert gas, such as argon, under a pressure of 600 to 700 mm. Hg.

A modification shown in FIG. 2 has a rating of 100 v., 500 w. and comprises a transparent cylindrical glass bulb having therein a tungsten coil filament 11 which is supported by a plurality of anchors 12 at points spaced apart along the length thereof in such a manner that the filament 11 extends along the longitudinal axis of the bulb. At both ends of the bulb are formed pinched portions 13 in which molybdenum foils 14 are hermetically sealed. Opposite ends of the filament coil 11 are connected through lead wires 15 and foils 14 which in turn are connected to terminal pins 16. A mixture of Argon gas and chloroform is sealed in the bulb. The pressure of the Argon gas may be of the order of 600 to 700 mm. Hg. and the amount of the sealed chloroform may be about 0.01 to 0.10 micromol per cubic centimeter of the inner volume of the bulb.

It is the essential feature of the invention that chloroform used as a halogen compound to be sealed in the bulb amounts to 0.01 to 0.10 micromol per cubic centimeter of the inner volume of the bulb, as will be explained more in detail in connection with the following experiments.

Experiment was carried out using a CHCI containing lamp having a rated voltage of v., a power of 500 w. and a rated life duration of 500 hours. With the lamp of such type, it is easy to observe such phenomena as blackening and etching since the temperature of the filament is relatively high and the diameter of the filament is thin.

In the experiment, a plurality of lamps were prepared by selectively sealing therein, together with argon used as an inert gas, 0.005 micromol, 0.01 micromol, 0.05 micromol, 0.10 micromol, 0.15 micromol and 0.20 micromol of CHCI per cubic centimeter of the inner volume thereof. The pressure of the gas charged in each of the lamps was maintained at 600 to 700 mm. Hg. The lamps were operated at a rated voltage of 100 v. and 10 percent overvoltage of v. The results are shown in the table below.

Amount of Working sealed CHCl voltage (micromol/emf) (volt) Remark 0.005 100 Blackening appeared 34 hours after ignition oi the lamp. 0.005 110 Same as the above 0.010 100 Blackening and etching did not appear I 1640 hours after ignition though the filament was burned out. 0.010 110 Same as the above. 0050 I00 Blackening and etching did not appear 1433 hours after ignition of the lamp. 0.050 110 Same as the third and fourth columns. 0.100 100 Blackening and etching did not appear I360 hours after ignition though the filament was burned out. 0.100 110 Blackening and etching did not appear 590 hours after ignition though the filament was burned out. 0.150 100 Etching appeared 500 hours after ignition. 0.200 100 Etching appeared 280 hours after ignition.

It will be apparent from the table that the amount of incorporation of CI-ICI of 0.01 to 0.10 micromol/cm. causes the lamps to be maintained at high efficiency without the occurrence of blackening and etching during the operative life thereof.

The amount of incorporation of chloroform according to this invention is selected to lie within the range of 0.01 to 0.10 micromol/cm. on the basis of the results of the foregoing experiments. The selection of the amount of incorporation at that range is due to the fact that lamps of a predetermined life will not be definitely produced due to production errors when said amount is closely out of that range. The range described will thus definitely permit lamps of a predetermined life to be manufactured at allowances of usual production errors permissible in the art.

In the foregoing table, the operative lives of some of the lamps were measured at the two different voltages. The overvoltage of 1 10 percent of the rated voltage was applied to consider the influence of the halogen dissociated due to a simultaneous rise in the temperature of the filament and that of the bulb. It was clearly observed that no blackening occurred within the range of incorporation of CHCl between 0.01 to 0. 10 micromol/cm", which is featured by this invention. It was also found that no damage was produced on the metallic elements, such as anchors, due to etching. As will be understood, the lives of the lamps tested by the overvoltage were obviously shorter than those of the lamps to which the rated voltage was applied.

Since an acceptable range of incorporation of a halide amounts widely to 0.01 to 0.10 micromol/emf, the yield of the product can be greatly increased. The lamp containing chloroform ofthe amount described can be maintained at high efficiency without the production of a blackening and/or etching phenomena. In particular, chloroform is stable against water, so that it will not cause various elements of the lamp, such as a filament and anchors, to be subject to etching, which will occur when hydrogen chloride is used. Since chloroform is an organic compound, it is likewise stable against any incoming foreign materials, so that a lamp containing such a compound exhibits an excellent halogen regenerative cycle.

ln consideration of various other factors, such as the relative amount of hydrogen and chlorine, and dissociation affected by the temperature of a compound among carbon, hydrogen and chlorine, separate experiments were carried out by additionally sealing an amount of hydrogen and chlorine, but no good results were obtained as being shown in FIG. 3.

Referring to FIG. 3, the chloroform (CHCH are indicated by a dotted line. Further, the proportions of hydrogen and chlorine when there were added excess amounts of hydrogen to the chloroform are indicated by marks of A and such proportions when there were added excess amounts of chlorine by marks of The aforesaid excess addition of hydrogen is r'ii'n'teifb the case A where there was added 0.03 micromol/cm. of hydrogen when the lamp contained 0.03 micromol/cm. of chloroform and the case B where there was added 0.03 micromol/cm. of hydrogen when the lamp contained 0.1 micromol/cm. of chloroform. In both cases, there appeared blackening in the lamps within 500 hours of use. On the other hand, the aforementioned excess addition of chlorine is denoted by the case C where there was added 0.1 micromol/cm. of chlorine when the lamp was filled with 0.04 micromol/cm. of chlorine and the case D where there was added 0.1 micromol/cm. as against 0.06 micromol/cm. of chloroform. The lamp presented etching in I00 hours with the case C and in 30 hours with the case D. in FIG. 3, the ordinate represents the amounts (g. atom/cm.") of hydrogen sealed and the abscissa the amounts (g. atom/cmx") of chlorine sealed.

What is claimed is:

l. A halogen lamp comprising a bulb, a tungsten filament mounted in the bulb, at least one gas selected from the group consisting of nitrogen and inert gases, and chloroform in the amount of 0.01 to 0.10 micromol per cubic centimeter of the inner volume of the bulb, the gas and chloroform being sealed in the bulb. 

